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Au 28, 192%.; mszme J. E. DSTLINE TELEPHONE SYSTEM Filed April 2, 1925 5 Sheets-Sheet :3

'r'o o sRAToRs INDUCTION con.

l'mreninr' John E1215 0.7mm

Aug. 28, 1928.

J. E. OSTLINE TELEPHONE SYSTEM 5 Sheets-Sheei 2 Filed April 2, 1925 12m EH15 UETZma Aug. 28, 1928.

J. E. OSTLINE TELEPHONE SYSTEM Filed April 2, 1925 5.5heets-Sheet 4 Aug, .28, 1928;. 11,682,1389

J. E.- OSTLINE TELEPHONE SYSTEM Filed April 1925 5 Sheets-Sheet- 5 Patented Aug. 28, 1928.

ilhll'l'EQ STATES I httzfith JOHN E. OSTLINE, OF LIVER-POOL, ENGLAND, ASSIGNOR, BY MESNE ASSIGNMENTS, TO AUTGMATIC ELECTRIC INC., OE CHICAGO, ILLINOIS, A COREORATION 0F DELA- TELEPHDNE SYSTEM.

Application filed April 2, 1925, Serial No. 20,035, and in Great Britain April 24, 1924.

This invention relates to improvements in automatic or semi-automatic telephone systems and more particularly concerns arrangements for transmitting tones to an operators'position by giving special signals in the case of calls being set up to dead numbers or other numbers which for any reason are unattainable or set up to busy hnes.

One featureyof the invention. concerns a novel arrangement for utilizing a tone current to bring about the intermittent operation of a supervisory signal- The particular advantage of this arrangement is that it is not necessary to make any alterations in the selectors, connectors or repeaters for transmitting an intermittent signal, such as a busy flash to an operators position to indicate the busy or faulty condition of a line or switch.

Another feature of the invention concerns a novel arangement for indicating to an operator the operated or non-operated condition of a device which connects up an impulse sender, the indicating device being also arranged to indicate the busy or faulty condition of a wanted line independently of the posit on of the key which connects up the impulse sender.

A further feature of the invention con cerns an arrangement for intermittently operating a supervisory signal to indicate the busy or faulty condition of a line or switch, by the connection of a booster batteryv potential to a speaking conductor at any stage of a connection, a tone current being superimposed on the speaking conductors to indicate whether the signal operated by the booster battery is being operated from a faulty or busy line; this arrangement has the advantage that no special trunk lines have to be provided for leading to operators positions for dealing with such classes of calls.

A further feature of the invention relates to an improved impulse repeater having a polarized relay for responding to reversals of current'and a non-polarized'relay for responding to booster battery, the polarized relay being adapted to effect the operation of a supervisory relay to indicate the. re,- sponse of a wanted party and the non-polarized relay to indicate the busy or faulty condition of a wanted line, the non-polarized relay being connected either in series or par allel with a winding of the polarized relay.

In order that the invention may be clearly understood and readily carried into effect a telephone system in accordance with the invention will be more fully described with reference to the annexed drawings which show some examples of the invention.

Referring non to the drawings comprising Figs. 1-10, inclusive," these figures show sufiicient of the circuits and apparatus of an automatic or semi-automatic telephone system to enable the various features of the invention to be clearly understood.

Figs. 1 and 2 show a part of a telephone system comprising a manual exchange and an automatic exchange. More in detail, Fig. l shows the calling end of an operators cord circuit 0 terminating in the plug P. Fig. 2 shows a trunk line extending from jack J in the manual exchange to the automatic exchange, terminatin thereat in a selector switch (not shown). Fig. 2 also shows the repeater BEAR associated with the trunk line. p l

1 Figs. 3-8, inclusive, when placed in numerical order from left to right, show the principal switches used to extend a call from an operators position at a manual exchange to a subscriber in an automatic exchange.

More in detail, Figs. 3 and i show the apparatus at the manual exchange, which is similar to that shown in Figs. 1 and 2.

F 5 and 6 show apparatus located at an automatic exchange which is located between the manual exchange and another automatic exchange. The selector S. Fig. 5, terminates the trunk from the manual exchange.

Fig. 6, shows an impulse repeater AAR associated with the trunk comprising conductors 279 and 280 which is accessible in the banks of selector S and which extends to a second automatic exchange.

Fig. shows apparatus located at the second automatic exchange. The trunk line comprising conductors 279 and 280 terminates in an incoming selector (indicated by the dotted rectangle) similar to selector S, Fig. 5. Since the functions of the incoming selector are identical to those of selector S,

Fig. 5, no further reference thereto will be made. The incoming selector has access to the final selector ES, shown in detail, which in turn has access to the subscribers lines. Fig. 8, directly below the final selector FS, shows the tone machine for giving busy and number unavailable signals.

Figs. 9 and 10 show or indicate the principal switches used to extend a call from a subscriber at an automatic exchange to an operators position at a manual exchange. More in detail, the rectangle C indicates a subscribers lines switch, The rectangle S indicates a first selector accessible in the banks of the line switch G. The repeater R is associated with a trunk accessible in the l anks of the selector S. This trunk extends to a second automatic exchange terminating tl'iereat in the incoming selector S indicated by a rectangle. The repeater R is associated with a trunk accessible in the banks of the selector S and extending to the operators position 0 terminating thereat in the jack J Fig. 10. The answering end of a cord circuit terminating in the plug P is also shown.

A detailed descrptionwill now be given ofthe arrangement whereby the usual busy tone current is utilized to operate a relay which inturn brings about the tranmission of a busy flash signal to an opcratofis position, reference being had to Figs. 1 and 2. IVhen the operator inserts the plug P of the cord circuit O, Fig. 1 into the jack J of the manual to automatic repeater MAR, Fig. 2, sleeve relays 203 and 200 energize in series over the following circuit: earth, relay 203,

sleeve of jack J, sleeve of plug I normally closed contacts controlled by spring 213, nor mally closed contacts controlled by spring 21 1-, relay 200 to battery. Relay 200, upon energizing, completes the following circuit for the supervisory lamp If, earth 217, 216, L battery. Relay 2023, upon energizing, completes at armature 218 a circuit for slow relay 205 and at armature 219 completes the following loop circuit across conductors 228 and 229; conductor 229, armature 219 and its working contact, lower right hand winding of repeating coil It, winding I of the shunt field relay SFR, upper right hand winding of repeating coil R to conductor 228. Slow relay 205, upon energizing, prepares at armature 220, a circuit for slow relay 204 and at armature 221 completes a circuit for the polarizing winding II of the shunt field relay SFR and the same time prepares a circuit for relay 206. Everything is now in readiness for the operator to dial the wanted Iiill1'1bB1,'Wl1O connects up the impulse sender or calling device CD by actuating the dialling key DK. The operation of the dialling key DK substitutes the calling device CD for the sleeve relay 200 at spring 21" and spring 214- connects the high speed flicker F in circuit with the sleeve relay 200 through resistance 212, while s rings 215 earth the common conductor CU.

he lamp If is now very rapidly flashed by the flicker F and a tone current is connected to the operators induction coil over conductor X by the operation of relay P which was energized'by the closure of springs 215. 1

Assuming that the first digit in the wanted number is 5 the operator will dial the digit 5 which will produce five interruptions in the circuit of sleeve relay 203. Relay 203 will accordinglyproduce at armature 219 five interruptions in the circuit of the line relay of the selector (not shown) connected across conductors 228 and 229, The first time relay 203 deenergizes it completes at armature 218 the previously prepared circuit for slow relay 204; slow relay 204, uponenergizing, provides a direct loop across conductors 228 and 229 for subsequent impulses, excluding the repeater R and the winding I of the shunt field relay SF R. Relay 204 also removes earth at armature 223 from one side of the condenser 209. The selector (not shown) connected across conductors 228 and 229 responds in known manner to the impulses dialled and then automatically hunts for an idle line in the selected level.

Assuming that all. the lines in the selected level are busy, the well known cam springs of'the selector will be operated on the eleventh rotary step to connect a busy tone current to conductor 229. The busy tone current is arranged to have a frequency of about 400 to 500 cycles per second andthis current operates the vibratory relay 207 as follows: conductor 229, armature 219, lower right hand winding of repeating'coil It, armature 252 and its resting contaetyarmature 226 and its resting contact, vibratory relay 207, condenser 209 to earth at armature 223, of slow relay 204 which at this time is in a deenergized condition. .Thevi bratory relay 207, upon energizing, removes the short circuit from relay 206 at arma ture 25,3, whereupon relay 206 energizes in the following circuit: battery, resistance 208,

relay 206, working contact and armature 221 to earth. Relay 206 upon energizing,- completes a locking circuit for itself at armature 225; at armature 226 opens the initial energizing circuit for vibratory relay 207 and at armature 227 connects interrupted battery over the following circuit to the op erators cord circuit 0, Fig. 1. Earth, battery, slow speed interrupter I, resistance 210, working contact and armature 227, upper left hand windingof repeating coil R, tip of jack J, tip of plug P, relay 201 to earth. Relay 201 operates its armature 217 in accordance with the interruptions produced by the slow speed interrupter I and flashes the lamp L The circuit of the lamp L at'this time is, iowever, rapidly interrupted by the high speed flicker F, but nevertheless the comparatively slow interruptions of armature 217 gives a distinctive busy signal to the operator. The busytone current may, of course, be connected up at a second or subsequent selector or at a repeater or connector; these switches will have well known circuit arrangements for connecting up a busy tone current which is arranged to operate the special alternating current or vibratory relay 20?. whereby the connecting up of the busy tone current at any stage of the connection causes a busy flash signal to be transmitted to the operators position,

Assuming that a connection is established to the wanted party without encountering any busy outlets, then, when the wanted party answers, the direction of current flowing over conductors 22S and 229 will be reversed invltnown manner whereupon the shunt field relay SFP will energize and armature 252 disconnect the vibrator relay 207 from the speaking circuit and at armature 224 short circuit the con lenser 209 whereupon the following loop circuit will be completed for relay 201: earth, relay 201, tip of plug it tip of aclt J, upper left hand winding of repeating coil R, armature 22d and its working contact, lower left hand winding of repeating coil R, ring ofjack J, ring of plug P, retardation coil 202 to battery. Relay 201 accordingly'enei gizes over this circuit and at armature 217 extinguishes lamp L thereby indicating to the operatorthat the wanted party has answered. Should the operator neglect to restore the dialling ltey BK after the necessary series of impulses have been transmitted, the operated condition of the dialling key is indicated to the operator by the rapid oftlie lamp L brought about by the tliclter F when the dialling keyis in its operated condition and moreover the tone current TC is connected to the operators induction coil over conductor X whenever thev dialling key is in an operated position. Whenthe conversation is finished and the calling and calledparties have replacedtheir receivers, the shunt field relay Sl lt will deenergize and open at armature 224 the circuit for relay 201. Relay 201 will deenergize and complete the circuit for lamp lamp L whereupon the operator will withdraw the plug from the jack 5', whereupon all energizefd relays in tae manual to automatic repeater MAR will deenergize. v From the above arrangement "t will be 1 seen that a novel and usefularrangement has been provided for utilizing a busy tone current to give a flashing signal to an o erators position. The great advantage of such an arrangement-is that standard se-.

lectors,-'repeaters and connectors may be .ing coil used without providing special arrangements for repeating a busy flash signal to an operator,

A detailed description will now be given of the booster battery method of transmitting a busy fiash signal from any stage of the connection to an operators position reference being had to Figs. 3-8, inclusive. The operators cord circuit 0 Fig. 3, and the manual to automatic repeater MAR, Fig. l, are identical with the cord circuit 0, and repeater MAR, Figs. 1 and 2, respectively, except that the relay 408 is connected in parallel with winding I of the shunt field relay 406, relay l08 responding only to a booster battery current.

For the purpose of this description it will be assumed that the operator at the cord circuit O dials the digits 2, 3, 4-, which will operate the selector S, Fig. 5, at the first automatic eXchange and the connector FS. 7, at the second automatic exchange to establish connection with a wanted party. When relay ace of therepeater MAR energizes the following circuit will be completed for relay 230 of the selector S, Fig. 5, battery,

upper winding of relay 230, resting contact and armature 238, conductor 430, upper right hand winding of repeating coil R, winding 1 of the shunt field relay 406 and relay 208 in parallel, lower right hand winding of repeat- R, working contact and armature 419, conductor 431, armature 239 and its resting contact, normally closed eleventh step cam springs CS, lower winding of relay 230 to earth. Relay 230, upon energizing, completes the following circuit for slow release relay 231; earth, 240, 242, 281, battery. Relay 231, upon energizing, first earths the holding. conductor 245 at armature 2% and at the bac; contact of armature 24:8 opens a point in the circuit of release magnet 237 and at the front contact of this armature prepares the operating circuits. The first series of impulses will be repeated by relay 230 to the vertical magnet over armatures 242, 243, and relay 232 to the vertical magnet 235. Slow series relay 232 energizes in series with vertical magnet 285 and remains operated throughout the series of impulses. Upon the first vertical step off normal springs 250 and 24. 9 close, the former pr pares a circuit for release magnet 237 and the latter completes the following circuit for stepping relay 233, battery, 249, 246, 2&5, 24a, earth. telay 233, upon energizing, completes a locking circuit for itself at armature 2&8 and at armature 247 prepares a circuit for the rotary magnet 236. At the end of this series of impulses relay 282 deenergizes and completes the rotary magnet circuit at the normally closed springs controlled by armature 246, whereupon the hunting operation takes place in lniown manner.

Assuming that all the lines in the selected level are busy, the cam springs CS and CS will be operated on the eleventh rotary step. The spring CS opens the circuit of switching relay 234 and springs CS connect the common busy conductor B through resistance 251 to conductor 431. Conductor B is connected to a busy machine similar to'the busy machine shown in Fig. 8, where it passes through the low resistance secondary winding of a busy tone induction coil, similar to induction coil BI,to booster battery, and consequently a busy tone current and abooster battery current are superimposed on conductor 431. The busy tone current will not serve any useful purpose in this connection, but the booster battery current will bring about the operation of relay 408 which as before mentioned only responds to an increased current. Relay 408, upon energizing, removes the short circuit from relay 407 at armature 428. whereupon relay 407 establishes a locking circuit for itself at armature 426 and at armature 427 opens the initial energizing circuit of 408 and at armature 425 connects up interrupted battery through the slow speed interrupter I, and resistance 409 to relay 401 of the cord circuit 0 which flashes the lamp L in unison with the interrupters produced by the interrupter 1.

Assuming now that the selector S, Fig. 5, finds an idle line in the selected level and that this line comprises conductors 260 to 262, inclusive, under these circumstances no circuit will be completed for stepping relay 233 upon the decnergization of slow relay 232, but instead the following circuit will be completed for switching relay 234; earth, 244-, 245, CS, 234, 253, 249, 233 to battery Switching relay 234 alone energizes in this circuit on account of the high resistance of relay 234. Relay 234, upon energizing, switches the speaking conductors through to the conductors 260 and 262 at armatures 238 and 239, respectively. These conductors lead to the automatic to automatic repeater AAR, Fig. 6, and at armature 241 the test wiper is connected to conductor 261. Relay 234 also at armatures 238 and 239 opens the circuit of relay 230 which in turn opens the circuit of release relay 231. Switching relay 234, however, is maintained energized by release relay 231 until earth is fed back over conductor 261 which occurs in the following manner.

When the speaking conductors 430 and 431 are extended to conductors 260 and 262, respectively, relay 265 energizes over the following circuit; battery, upper winding of relay 265, normally closed contacts controlled by armature 267 conductor 260, armature 238 and its working contact, conductor 430, the loop circuit in the repeater MAR, conductor 431, armature 239 and its working contact, conductor 262, normally closed contacts controlled by armature 269, normally closed contacts controlled by armature 268, and the lower winding of relay 265 to earth. Relay 265, upon energizing, completes a circuit for slow relay 263 at armature 273 and at armature 272 connects thetollowing loop circuit across conductors 279 and 280 which lead to the final selector FS, Fig. 7, exclusive of resistance 274, Fig. 6; conductor 279, upper Winding of relay 266, right. hand winding of shunt field relay SFR, lower winding of relay 266, resting contact and armature 271, working contact and armature 272 to conductor 280. Slow relay 263, Fig 6, upon energizing, earths the release trunk conductor 261, at armature 278, thereby establishing the usual holding circuit for switching relay 234 of the selector S before the slow release relay 231 has had time to deene-rgize; at armature 276 completes a circuit for the polarizing winding of the shunt field relay SFR and at armature 277 prepares a circuit for slow relay 264.

When the previously traced loop circuit was completed across conductors 279 and 280, relay 283 energized in the circuit including the normally closed contacts controlled by armatures 294 and 295 of the back bridge or reversing relay 282. Relay 283, upon nergizing, completes a circuit at armature 296 for slow release relay 284; relay 284 prepares the impulsing circuit at armature 299 and at armature 298 prepares a holding circuit and at armature 297 earths rcleasetrunk conductor 281 in order to mark the final selector FS engaged. The operator may now dial the next digit in the wanted number, whereupon the hereinbefore described results will take place in the manual to automatic repeater MAR, Fig. 4. At the. first interruption of the speaking conductors 430 and 431, the circuit of relay 265, Fig. 6, is opened. Relay-265 will open the circuit of relay 283, Fig. 7, at armature 27 2, and relay 283 transmits one impulse to the vertical magnet 291 in the following circuit; earth, 296, 299, 326, 324, 285, 291, battery. Relay 265, Fig. 6, upon deenergizing in response to the first impulse will also complete the previously prepared circuit forrelay 264. Relay 264, upon energizing, connects a direct loop across conductors 279, 280, excluding the winding of relay 266 and SFR. Subsequent impulses to vertical magnet 291 are repeated by relay 283 and relay 283 transmits them over the circuit: earth, 296, 299, 326, 327, 300-, 285, 291, to battery. Oil normalsprings 324-327, inclusive, operate on the first vertical step and relay 285 energizes in series with the vertical magnet and remains energized throughout the series of impulses. In response to this series of impulses the Wipers 329 to 331, inclusive, are raised opposite to the third level of bank contacts.

At the end of this seriesof impulses relay relay 289 is energized in parallel with the rotary magnet over the back contact and armature304 of relay 287 and remains energized during the transmission of this impulse series. Relay289 at armature 316 closes the previously mentioned point in the impulsing circuit andat armature 315 completes acircuit for slow relay 288 as follows: earth, 315, 307, 288, battery; and at armature 314 opens a point in the circuit of switching relay 290. Belay 288, upon energizing, opens at armature 328 the path over which the first impulse was transmitted to the rotary magnet, at armature 312 connects the busy tone and booster battery conductor BT to armature 309 of relay 287 through resistance 323; at armature 311 prepares a locking circuit for itself and at armature 310 completes a circuit for the upper Winding of tw0-step relay 287. Two step relay 287 being marginally adjusted only operates armature 308 in this circuit. Shortly after the termination of the final series of impulses to the rotary magnet 292, relay 289 deenergizes and opens at armature 315 the circuit for slow relay 288; at armature 314 closes a point in the circuit of switching relay 290 and at armature 313 closes a point in an alternative circuit of relay 288.

it the wanted line is free there will be no earth potential on its test wiper 330 and switching relay 290 will energize over the following circuit: earth, 298, lower windingof switching relay290, resting contact and armature 314, resting contact and armature 306, test wiper 330 through the cut oil relay and driving magnet of the line switch (not shown) of the wanted partys line. Belay 290, upon energizing, completes a locking circuit for itselfat-armature 32.0; at the back contact of armature 321 opens a point in the circuit for fully energizing the two-step relay 287; at the front contact of the 'same armature short circuits its lower winding; and at armatures 317 and 322 connects the wipers 329 and 331, respectively, to a source of ringing current. The ringing current is fed over conductor 322 through the upper winding of ring cut oil relay 286',

' resting contact and armature 301, working contact and armature 317 and wiper 329 to one side of the subscribers line and returns over the other side of the subscribers line, wiper 331, armature and its working contact, armature 303 and its resting contact to battery. The operation oftne ringing current is fed backto the operatofis position over armature 318- and its working contact and small capacity condenser c.

When the ca led party answers ring trip relay 286 operates, closes a locking circuitfor itself at armature 302 and at armaturcs 301 and 303 completes the talking connection. A'further result of the: operation of relay 286 is the completion of the circuit for back bridge relay which energizes over the called subscribers loop and reverses the direction of current over conductors 279 and 280 whereuponthe shunt field relay SFR in the automatic to automatic repeater AAR energizes in series with relay 266, but relay 266 being marginally adjusted does not ener 'ize at this time. I

reverses the direction of current over conductors 260 and 262 at armature 267 and 268, respectively, whereupon the shunt field relay 406 in the manual to automatic repeater BEAR energi'zes and completes a circuit at armature 424 for relay 401 in the cord circuit 0 Relay 401, upon energizing, opens the cir cuit for the supervisory lamp L 'thereby informing the operator thatthe called partv has answered.

The operator will in the meantime have restored the dialling key DK, the lamp L having glowed steadily until the called party answered. Should the operator neglect to restore the dialling key DK a circuit will be completed for the lamp L through the flicker F thereby guarding against the dialling key being left in its operated posi tion. 1

When the conversation is finished and the called party replaces his receiver, the back bridge relay 282 deenergizes and restores the direction of current over conductors 279 and 280 to normal whereupon shunt field relay SFR of the automatic to automatic repeater AAL deenergizes and reverses the direction of current over conductors 260 and 262, whereupon shunt field relay 406 in the manual to automatic repeater MAR deenergizes and opens a pointin th circuit of relay 401 of the cord circuit 0". Relay 401 upon-deenergizing completes a circuit for the supervisory lamp L whereupon the operator withdraws the plug P from the jack J" bringing about the release of sleeve relav 403. Sleeve relay 4033, upon deenergizing, opens the circuit'of slow relay 405 at armature 418 and at armature 419 opens the loop circuit extending over conductors 430 and 431, whereupon relay 265 in the automatic to automatic repeater, Fig. 6, de-

opens the circuit of slow relay 263 at armature 273 and at armature 272 opens the loop circuit extending to the connector FS, Fig. '7. Slow relay 263, upon deenergizing, removes earth from release trunk conductor 261, whereupon selector S is released in known manner and in the final selector FS relays 283 deenergizes as a result of the loop circuit which opened at armature 272 of relay 265. Relay 283, upon deenergizing, opens thecircuit of release relay 284 and relay 284, upon decnergizing, removes earth from test conductor 281 at armature 297 and at armature 298 removes earth from the local holding conductor; at armature 299 completes the following circuit for release magnet 293: earth, 296, 299', off normal springs 325, release magnet 293 to batter l y the operation of the release magnet 293 the wipers 329-331, inclusive, are restored to normal, the off normal springs 325 opening the circuit of the release magnet in normal position.

Let us assume now that the line of the wanted party is busy. when connection was established therewith. Under these conditions there is an earth potential on wiper 330 and switching relay 290 is short circuited upon the de-energizationof slow relay 289. Shortly after the de-energization of relay 289, relay 288 de-energizes and removes the short'circuit from the lower winding of the two-step relay 287 at armature 310. Switching relay 290 being at .this time de-energized'the following circuit for fully energizing relay 287 is completed: bat,- tery, upper and lower windings of relay 287 in series, working contact and armature 308, resting contact and armature 321 to earth at armature 298. Relay 289 upon fully energizing operates its armatures 304, 305, 306, 307 and 309, and at armatures 307 and 306 completes the following circuit for relay 288; battery, 288, 307, normally closed contacts controlled by armature 311,- 313, 306, test Wiper 330 to earth. Relay 288, upon energizing, connects booster battery and busy tone to relay 266 of the automatic to automatic repeater Fig. 6, as follows: boost-v er battery BB, Fig. 8, secondary winding of busy tone induction coil BI, conductor BT,

working contact and armature 312, resist nsane tacts controlled by armature 267, to the up per winding of relay 265 to battery and earth. It will be noted that winding I of relay 406 is in parallel withrelay 408 but relay 406 of the shunt field type does not energize with increased current. Relay 408 upon energizing removes at armature 428 the short circuit from relay 407 and relay 407 brings about the transmission of interrupted battery to relay 401 which in turn flashes the lamp L in the manner previously described. transmitted to the operator over the speaking conductors and the operator is thus given a visual as well as an audible signal indicating that the. wanted line' is busy.

A detailed description will now be given of the operations which take placewhen a connection is established with an out of order or faulty line. l/Vhen a faulty line is discovered or when any line is to be placed out of order, the exchange attendant removes the battery connection from the cut-off rclay. Let us assume then that the final selector establishes a connection to a faulty line. Under these conditions neither battery nor earth will be found by the test wiper 330. WVhen slow relay 288 de-energizes shortly after the .de-energization of slow relay 289 it removes the short-circuit from the lower winding of the two-step relay 287 at, armature 310 whereupon relay 287 energizes over both its windings in series and operates armatures 304, 305, 306, 307 and 309. Armatures; 306 and 307 this time do not complete a circuit for slow relay 288 as there is no earth potential on wiper 330. Relay 289 will however energize again but its operation does not serve any useful purpose at this time. With relay 287 energized and relay 288 de-energized booster battery is connected to. conductor 280 as follows: boost- The busy tone current is also er battery, Fig. 8, low resistance secondary winding of the number unobtainable tone induction coil NUI, tone conductor NUT, resting contact and armature 312, resistance 323, armature 309 and its working contact to conductor 280. Since the same booster battery is connected to conductor 280 the hereinbefore described operations will take place in the repeaters AAR and MAR and the lamp L will be flashed as before, the

tone current superimposed on the speaking conductors will however be'characteristic of number unobtainable and the operator can then inform the calling party that the wanted line is out of order.

A description of the number unobtainable and busy tone circuit will now be given reference being had to 8. X is a high speed interrupter and '11:. slow speed interbooster battery BB while the other side of each secondary 18 connected to the common busy tone conductor BT, and the'com'mon number unobtainable tone conductor NUT, respectively. 7

A description will now be given of the re peater R F 9, which may be taken into use either in a connection from an automatic exchange to a manual exchange or from a. manual exchange to an automatic exchange, as well as in automatic to auto matic exchange connections. In the first case it is very desirable that the calling subscriber can attract the operators attention by slowly operating the switch-hook in the same way that an operator is signalled in 30' I the switches involved in the connection and one feature ct the repeater it is the provision of suitable holding arrangements wh ch prevent the release of a connection while at the same time give switch-hook supervision. When the repeater R is taken into use in a connection between a manual exchangeand an automatic. exchange, it is very desirable that the busy or number unattainablecondition of a wanted line or group of lines be indicated visually as well as audibly to the operator, and further feature of the repeater R is the provision 01" suitable arrangements enabling the repeater to perform either of these functions dependent upon whether it is taken into use in a connection from an automatic or; hangs .with switch-hook supervision, a detailed description or a connection between an automatic subscriber and manual operator will now be given with reference to Figs. 9 andfllO. reference character indicates an automatic subscribers rotary line switch of known type'and the reference character S indicates a first selector switch also of known type. The repeater is the repeater previously referred to and S a selector switch of known type similar to the selector switch S. The repeater l? and the operators position 0 form no part of the present invent present application in order that the holding feature of repeater B may be fully e pl I. led.

It is assumed that the subscriber whose line terminates in the line switch C desires to establish a connection with the operators position O 10, and that the selector switch S taken into use by the repeater n Under these conditions, relays 458 and 454 will energize in series over the normally closed contact-s controlled by armatures 168 and 169 of the shunt field polarized relay and the speaking conductors leading to Relay me calling subscribers station. upon energizing completes a circuit at armature still for slow release relay 450 and relay 45 i completes a loop circuit across conductors 513 and 515 leading to the selector switch 53. Slow relay 450 upon energizing earths the release trunk conductor 471, thereby rendering the repeater l 3 busy, and holding the switches s and C operated; at armature 461 prepares a circuit for slow relay 451 and at armature 462 completes an energizing circuit for the polarizing winding or relay 4-55. The double wound line relay (not shown) of the selector S energizes over the following loop circuit which was completed at armature 46'? by the operation of relay @554; battery, winding of line relay of the selector S, conductor 513, upper winding of marginal relay 456, right hand winding of shunt field relay e55, lower winding of relay 456, resting contact and armature 470, working contact and armature L67, conductor 515 to the other winding of the line relay of the selector S, and earth. The line relay or" the selector S alone energizes in this circuit-and prepares tie selector for operation in the usual manner. The shunt field relay does not energize owing to the direction of current through its right hand winding and relay e56 being marginally adjusted only responds to booster battery impulse'which is connected to conductor 15 whenever the selector S finds all lines of agroup engaged. In the present case if the selector S found all lines engaged, the operation of the marginal relay 156 would have no effect. Since the call originates in an automatic exchange the usual busysignal would be transmitted over the speaking conductors to the calling subscriber.

The calling subscriber may now dial the necessary ser es of impulses to ope "ate the selector S. Relays 453 and respond to the interruptions produced by the calling device in transmitting this digit. Relay n, and are shown in the Luelays 450 and 451 being slow to release remain energized throughout the transmission cl impulses. The selector S operates in known manner to select an idle trunk leading to the repeater B". At the end of the series of impulses. transmitted to the selector S, slow relay 451 deenergizes and removes the direct loop from conductors 514 and. 515 and when the selector I" finds an idle trunli'wl ich we will assume is the trunk comprising conductors 513 to 515., inclusive,

. relavs .516 and 517 energize over the i'ollowing circuit: battery, inding of relay conductor 513, conductor 513, upper w nding of marginal relay 456, right handw u ding 01 shunt field relay 455, lower win ing of relay 456, resting contact and armature 470, working contact and armature 467, conductor 515', conductor 515, winding of re lay 517 to earth. Relay 517, upon energizing, completes a circuit for slow release relay 518, and relay 516, upon energizing, connects the upper winding of relay 519 to the upper speaking conductor of repeater R at armature 526, and at armature opens a pointin the locking circuit for re lay 517. Slow relay 518, upon energizing, earths release trunk conductor 5.14 at armature 528 to mark the repeater R engaged and completes a holding circuit for the selector S and at armature 530 connects artiticial ringing induction to conductor 513 from the ringing tone machine RT and through the ringing tone condenser RTC in order that the calling party may receive a ringing tone when dialling a manual exchange. At armature 529 relay 518 also completes the following circuit for the calling relay 520 at the operatofis position 0 ear h, lower winding of relay 519, working contact and armature 529, trunk conductor 530, armature 532 and its resting contact, winding of relay 520 to battery. Relay 520 energizes in this circuit but relay 519 does not energize over its lower winding on account of the high resistance of relay 52-0.

llielay 520, upon energizing, completes a circuit at armature 533 for the calling lamp CL. The operator, upon seeing the lighted condition of the calling lamp, insertsthe plug P into the jack J whereupon a cirlruit is completed for relay 521 over the sleeve of jack J sleeve of plug P, relay 522 to battery. Relays 521 and 522 energize in. series, the former opens the circuit of relay 5 20 whereupon the calling lamp CL is extinguished and the latter prepares a circuit for the supervisory lamp SL at armature 534. \V hen the plug P was in and 523 energize over this circuit, the foriner disconnects the ringingtone from conductor 513 at armature 535, and at armature 536 pre mres a locking circuit for relay 517 and the latter opens a point 1n the circuit ol the supervisory lamp SL at armature 537 I.

A connection is now completed to the operator who converses with the calling party and completes the connection in known manner: The polarized relay 455 in the repeater it" is not energized as no reversal has taken place over conductors 513 and 515.

Assuming the calling party desires to attract the attention of the operator by slowly operating his switch-hook and thereby deenergizing relays Y453 and 454 of the repeater relay 454 at armature 467 connects relays 452 to conductor 515, and at the same time opens the loop circuit for relays 516and 517 of the repeator R relay 516 upon deenergizing closes a locking circuit for relay 517 at armature 525 over armature 536 and resistance 538 to battery. Relay 517, therefore, maintains slow relay 518 energized which in turn holds the selector S in an operted condition. The deenergizationof relay 516 also at armature 525 connects battery over resistance 538, armature 536 and its working contact, resting contact and armature 52", conductor 515, conductor 515, armature 467 and its resting contact to relay 452 and earth. Relay 452, upon energizing, earths the release trunk conductor 471,.t-hereby maintaining the switches S and C in an operated condition, independently of the re? lease relay 450, which relay will not fall away immediately upon the deenergization of relay 453, but will do so if the subscribers loop' isopened for a sufficiently long period,'as' would occur by the slow-operation of the switchhook. The continued slow operation of the switchhook will cause relay 516 to deenergize and energize in unison with the operation of the switchhook and at armature 526 it will open andclose the circuit of relay 523, and relay 523 will intermittently operate the supervisory lamp SL, thereby drawing the operators attention by the flashing of the lamp in a similar manner to the flashing of a supervisory signal which takes place in an ordinary manual system. The operator, upon seeing the flashing supervisory lamp, will operate her listening key (not shown) and Converse with the calling subscriber. From the foregoing it will be apparent that the release of the connection is under the control of the operator as relay 519 is energized over its lower winding in series with relay 523 at the operators cord circuit. lVhen'the calling party hangs up, relays 452, 453, and 516 deenergize, and re lay 516 at armature 526 opens the circuit for relay 523 which deenergizes and completes a circuit for the supervisory lamp SL which now grows steadily. When the operator gets the clearing signal from the called party she will withdraw the plug P from the jack J whereupon relay 519 will deenergize and open the locking circuit for relays 517 and 452.

When the repeator R is taken into use from a manual exchange, the busy flash feature is brought about in the same manner as described with reference to the automatic repeater. AAR, Fig. 6, that is if the selector S finds all lines of a group busy, it connects booster battery to conductor 515 which brings about t-he operation of marginal re lay 456 and this relay in turn connects booster battery to a speaking conductor lead ing to the operators position. If a connection is set up from an automatic subscriber in another exchange over the repeater R the operation of the shunt field polarized relay 455 will take place when the wanted party answers due to the reversal'of current over the speaking conductors 513 and 515, and will reverse the direction of current over the speaking conductors leading to the calling subscriber and may be utilized to bring about the operation of his meter to register the call.

What I'claim is:

1. In a telephone system, an operators cord circuit for extending calls to called lines, a dialing key in said cord circuit for connecting an impulse sender to said cord circuit, a supervisory signal, means for op erating said signal to indicate the busy or faulty, or idle condition of a called line, and means for operating said signal to indicate the actuated or deactuated condition of said dialing key.

2. In a telephone system, an operators cord circuit for extending calls to called lines, a dialing key in said cord circuit for connecting an impulse sender to said cord circuit, a supervisory signal, means for operating said signal to indicate the busy or faulty, or idle condition of a called line, means for operating said signal to indicate thefactuated or deactuated condition of said dialingv key, and means responsive to the actuation of said dialing key for connecting 3. In a telephone system, an operators position, means for extending a connection from said position'via trunk lines in successive stages, means for sending current impulses back over the extended trunk line at any stage, and means at said operators position responsive to the first of said current impulses for intermittently operating a supervisory signal at said operators position.

4. In a telephone system, an operators position, a trunk line comprising two inductively coupled sections, means for extending a connection from said operators position via said trunk line, means for sending alternating current back over the outer section of said trunk line, a relay bridged across the outer section of said trunk line responsive to said alternating current, means controlled by said relay for sending an interrupted direct current over the inner section of said trunk line, and a supervisory signal at said operators position responsive to said inter rupted direct current.

5. In a telephone system, an operators position, a cord circuit, a trunk line, means tor extending a connection from said position via said cord circuit. and said trunk line, a signal in said cord circuit, means for sending signalling current back over said trunk line apparatus for automatically and intermittently operating said signal, means for starting the operation of said apparatus responsive to said signalling current, said apparatus operating thereafter independently of said starting means.

6. In a telephone system, anoperators position, a trunk line, means for extending a connection via said trunk line to a called line in successive stages, means for causing a flow of current over said trunkline during the extension of said connection, means for changing the character of the flow of current over said trunk line at any stage in the extension of said connection, and means at said operators position initially operative responsive to said change in the character of the flow of currentover said trunk line for intermittently operating a supervisory signal at said operators position, said last means operating thereafter independent of the character of current flow over said trunk line.

7. In a telephone system, means for establishing a connection from an operators position to a called line, means for testing said line, means responsive to the finding of a busy or faulty condition of said called line for sending a signalling current over the talking conductors of said connection to operate a signal at said operators position, and means responsive to the finding of a faulty condition for sending another signalling current over the talking conductors to operate said signal and to produce a tone an audible tone to the operators head set, in the operators receiver.

y 8 In a telephone system, means including a trunk line for establishing a connection from an operators position to a called line, means for testing said line, means operative when an abnormal condition of said line is found for superimposing one of two kinds of signalling current on the talking conductors of said trunk line, the kind of signalling current being determined by whether the abnormal condition is a busy condition of the line or a faulty condition of the line.

9. In a telephone system, means for establishing a connection from an operators position to a called line, means for testing said line, means operative when said line is found busy or faulty for sending a characteristic current over the talking conductors of said connection, means operative when the called subscriber responds for reversing the normal current flow over the talking conductors of said line, a signal, a relay bridged across the talking conductors of said connection at said operators position and responsive to said characteristic current for controlling said signal, and a second relay connected in parallel with said first relay responsive to reversal of current in said talking conductors for controlling said signal in a diiierent manner. I

10. In a telephone system, an operators position, a trunk line, means for establishs ing a connection from said position via said trunk line to a called line, a signal at said position, a relay bridged across the conductors of said trunk line at said position operative in response to the removal oi the receiver at the called station for operating said signal, and a second relay connected in parallel with said first relay responsive to the finding of the called line busy for operating said signal in a different manner.

11. In a telephone system, a repeater, a polarized relay and a marginal relay bridged across the talking conductors of said repeater, means for controlling both relays over the outgoing side of said repeater, and a signal controlled differently by each of said relays.

12. In a telephone system, means for establishing connection from an operators position to a called line, means responsive to the busy condition of the called line for altering the character of the normal current flow over the talking conductors of said connection, means responsive to the removal of the receiver at the called station for reversing the normal current flow over said talking conductors, a non-polarized relay at said operators position responsive to said altered current flow for operating a signal-to indicate the busy condition of the called line, and a polarized relay at said operators position responsive to said reversed current flow for operating said signal to indicate the response of the called subscriber. I j

13. In a telephone system, automatic switches in an automatic exchange, a repeater in said automatlc exchange, an opera by said line relay and the operator at said position.

14. In a telephone system, a repeater adapted to be used in a trunk line for establishing a connection from a substation in an automatic exchange to an operators position, or in a trunk line for establishing a connection from an operators position to a substation in an automatic exchange, means in said repeater operative responsive to the replacement of the receiver at the substation for maintaining the connection intact and for signalling the operator when sa d repeater is used in a connection of the first type, and means in said repeater for increasing the normal current flow over the connection when a busy or faulty condi tion is encountered on the line to the sub station to operate a signal at the'oper'ators position when said repeater is used in a connection of the second type.

15. In a telephone system, means including a link circuit for extending a connection, a calling device, means for connecting said calling device with said link circuit, a signal, means responsive to the encountering of a particular condition during the extension of the connection for controlling the operation of said'signal, and means for controlling the operation of said signal to indicate when said calling device is connected to said link circuit.

16. In a telephone system, a calling de vice, means including trunklines for extending a connection in successive stages by operating said calling device, means for distinctively marking a trunk line at any stage, a signal, and means responsive to a trunk line being marked for operating said signal when said calling device is being operated.

17. In a telephone system, means including trunk lines for extendin "a connection in successive stages, means or applying a a characteristic potential'to a conductor of a trunk line at any stage, a'signal, and means immediately responsive to said application at any stage for intermittently operating,

said signal. 7

18. In a telephone system, trunk lines,

means for serially connecting said trunk lines to extend a connectlon, means for applying a characteristic potential to a conductor of any trunk line, and means associated with the first trunk line and initially responsive to said application to a conductor of any trunk line for applying a different,

characteristic potential to a conductor of the first trunk line, said last means operating thereafter independent of the potential on said conductor.

19. In a telephone system, means includ ing trunk lines for extending a connection in successive stages, means for applying a characteristic potential to a conductor of a trunk line at any stage, a signal, and means initially responsive to said application at any stage for operating said signal, said last means operating thereafter independent of the potential on said conductor. 7

20. In a telephone system, a trunk, a line, means including an automatic switch for extending a connection from said trunk to said line, means in said switch for applying a characteristic potential to a conductor of said trunk providing the line is busy, and

for applying a different characteristic potential to a conductor of sa1d trunk providing the line is faulty.

ill

21. In a telephone system, a line, means including a trunk for extending a connection to said line, a polarized relay and a marginal relay bridged across the conductors of said trunk, means for causing the operation of said marginal relay operative providing the line is in a particular condition when the connection is extended thereto, means for causing the operation of said polarized relay when the call is answered, and a signal controlled differently by said relays.

22. In a telephone system, a line, an auto matic switch for extending a connection to said line, a test relay in said connector for connecting either one of two characteristic potentials to a talking conductor of said connector, and means operative, providing the line is busy when connection is extended thereto, for determining which of said two characteristic potentials will be connected to said conductor.

In witness whereof, I hereunto subscribe myname this 16th day of March, A. D. 1925.

' JOHN E. OSTLINE. 

